Radio receiving apparatus



July 20 1926.

`R. A. RIDENOUR RADIO RECEIVING APPARATUS Filed June; 28, 1924 Patented July 20, `1926.

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RANDOLPH A. RIDENOUR, OFCOLLGE CORNER, OHIO.

RADIO RECEIVING .AP?ARATUS.

Application led June 2.8, 1924. Serial No. 722,931.

The object ofy myinvention is to provide method and `means for .eliminating static disturbance and interference in radio receiving apparatus and thus produce clearness and distinctness in the received signals.

Another object of my invention is the provision of method and meansfor increas-` ing the lreceiving power of radio receiving apparatus whereby signals from distant stations kmay .bey received with distinctness either with or Without the use of the conventional type of aerial.

I'accomplish the above yand other objects of my invention, whichwill be apparent as the description proceeds, by means of the apparatus shown in the accompanying drawing, which is a diagrammatic view of one embodiment of my improved apparatus.

Referring to the drawing, l indicates the antenna of a radio receiving apparatus, 2 the primary winding ofthe induction coil and 3 the secondary winding thereof.

Across the terminals of the secondary coil is connected the condenser 4 of approximately .00027 mf. This condenser effectuates sharp tuning of the circuit in which is located the conventional grid condenser and leak 5 and the grid 6 of the tube 10. The tube 10 acts as a radio frequency detector ahead of the first stage of radio frequency amplification, while the condenser 4 controls the output of the tube 10.

The plate 8 of the tube 10 has included in its circuit the primary winding 1l and is connected to the positive terminal of the B battery of 221A;J volts. The plate circuit of the tube 10 passes directly over the second ary circuit of the tube 20. The filament 7 of the tube 10 is connected t0 the negative terminal of the A battery and has in its circuit the filaments of the tubes 20, 80, 40, 50, etc. The primary windings 2 and 11 preferably contain seven turns, while the secondary windings 3 and l2 of the induction coils preferably contain sixty-seven coil turns.

The secondary winding 12 of the induction coil has shunted across its terminals the condenser 13 and is connected to the grid of the tube 20. The condensers t and 13, which are preferably eleven plate condensers, constitute the means for tuning the output circuit so that it is resonant to the desired wave length. In practice, the detector tube 10 is tuned through the condenser 4L and the radio frequency tube 2O is then tuned to the same wave length through the condenser 13. This eliminates the undesired Waves and the interfering spark stations t0 a great extent and makes for clearness of the received signal.

rilhe primary winding 11 is connected to the positive side of the B battery, as stated above, the primary winding of the transformer 51 of the audio circuit being in the same circuit therewith.

. The radio frequency transformers may be of any Well known type and are constructed for operation at any desired wave length over a .wideband of wave lengths.

The potentiometer is connected as shown in the secondary circuit of the induction coil 2, 3, the filament circuit of the tube 10 and the battery A. The negative terminal of the A battery is in the filament circuit of the detector tube 10.

The grid return of the first three tubes is in the positive side of the filament circuit while the grid return of the remaining tubes is in thel negative side of the filament circuit.

It will thus be seen that the first tube l0 of my improved radio receiving apparatus acts as a detector of radio frequencies, the tubes 20, and 40 functioning as radio frequency amplifiers; the first two tubes 10 and 2O constitute the portion of the apparatus that may be tuned to receive the desired wavelengths and eliminate the undesired waves. The tube functions as a second detector, the remaining portion of the apparatus (here shown as tubes and 70 and their connections) constituting the audio amplifier. While I have shown a condenser 52 across the primary of transformer 51, such an arrangement is not an essential part of my construction and may be omitted when desired.

75 indicates ear phones or other suitable transmitting instrument.

By amplifying at radio frequency according to my improved method and apparatus, many superfluous noises are eliminated and a much clearer signal is obtained than lin methods and apparatus wherein the signal is initially rectified and amplied at audio frequency.

With the arrangement shown it is obvious that any suitable form of tubes and transformers may be employed in the building of my improved radio receiving apparatus, as well as any desired form of audio amplifier, and the drawing and the description thereof are therefore to be considered as merely illustrative of an arrangement ofv parts which will accomplish thev objects ofmy invention.

lVhile I have shown my improved apparatus in connection With an aerial, it is to be noted that it will operate effectively'4 either' with or Without the same.

Having thus described my invention, what I claim as new' and desire to secure by Letters Patent is l; A method of selective signa-l receptiony r'eeeivinfr circuit com )risiner a jluralit ofl three element tubes, means comprising a grid leak-condenser unit associated with the first of said tubes, said'` unit being of such impedance as to cause it to partially detect incoming high frequency waves and means including a radio frequency transformer in the output of said tube for passing the undetected potin of said high frequency waves to succeeding amplifier tubes.

mult'i-stage1 tuned radio receiving circuit comprising a plurality of three element' tubes, means-comprising' a grid leakcondenser unit aoc'i'ated with the first of said tubes, said unit being of such impedance as to cause it to partially detect incoming liig'h frequency Waves,V and means includinga radio fre uency transformer in the output ofl said tube' for passing' the undetected portion of s'id l'iig'liy frequency Waves to succeeding' amplifier tubes, and means including other' of said tubes to r'e'- detect and amplify' said' waves at audio' frequencies. v l

Iitestim'onyjvhereuf I ax' ni signature.

RN'DOLPH RID NOUR. 

